X.P    4 


c-3 


Press  Bulletin   Series  Issued  Twice  Quarterly 


STATE  OF  ILLINOIS  \Cjfi* 

V  \    1  » 


DEPARTMENT  OF  REGISTRATION  AND  EDUCATION  .  Q^      . 


A.  M.  SHELTON,  Director 


\Q&^  *  ^ofifr 


DIVISION  OF  THE  *\X^      \1\^    O  V  ° 

STATE  GEOLOGICAL  SURVEY      ^$&tf$> 

M.  M.  LEIGHTON.  Chief.   Urbana 


No.  4  ILLINOIS  PETROLEUM  August  28,  1926 


CONTENTS 

PAGE 

Areas  for  further  prospecting  near  the  Martinsville  pool,  Clark  County 1 

Oil  investigations  in  the  Centralia  area — preliminary  report 6 

AREAS   FOR  FURTHER  PROSPECTING  NEAR  THE  MARTINS- 
VILLE POOL,  CLARK  COUNTY 

By  Gail  F.  Moulton 

Introductory  Statement 

Areas  deserving  further  prospecting  in  the  vicinity  of  the  Martinsville 
pool,  Clark  County,  were  determined  as  a  result  of  a  field  investigation  by 
the  Illinois  State  Geological  Survey  during  1925  and  1926.  The  present 
preliminary  report  is  issued  so  that  the  operators  interested  in  the  field  may 
benefit  at  once  from  the  results  of  the  work.  A  report  to  be  published  later 
will  present   further  details  regarding  geologic  conditions  and  production. 

Development  of  the  Martinsville  Pool 

Prior  to  1922  the  production  in  the  Martinsville  pool  had  been  obtained 
from  a  pay  in  the  Mississippian  limestone  at  a  depth  of  about  500  feet. 
Late  in  1923  drilling  was  undertaken  to  test  the  oil  possibilities  of  the  "Tren- 
ton." The  Trenton  Rock  Oil  and  Gas  Company  found  such  a  good  show- 
ing of  oil  at  about  1,400  feet  in  their  first  well  on  the  John  Carper  farm  in 
sec.  30,  T.  10  X..  R.  13  W.,  Martinsville  Township,  that  drilling  was 
suspended  and  a  producing  well  obtained  in  the  newly  discovered  pav. 

Development  of  the  Carper  sand  production  was  active  during  the  per- 
iod 1923-1925.  During  that  time  a  deepened  well  discovered  a  new  produc- 
ing horizon  at  a  depth  of  1,550  feet  in  the  "Niagaran"  lime  and  within  the 
past  year,  many  wells  have  been  deepened  to  this  new  pay.  The  present 
practice  is  to  drill  both  the  Carper  and  "Niagaran"  horizons  at  once,  leaving 
about  200  feet  of  hole  without  casing  which  is  protected  by  a  liner  in  most 
cases  set  on  a  shoulder  at  the  top  of  the  lime  above  the  lower  pay. 


2  ILLINOIS   PKTKOLEI'M 

Producing  Horizons 
carper  sand 

The  Carper  sand  is  a  fine  grained  sandstone  which  occurs  in  lenticular 
bodies  of  considerable  areal  extent  in  the  black  shale  underlying  the  Missis- 
sippian  limestone.  The  general  relations  are  indicated  in  the  typical  section 
in  figure  1.  Commonly  the  sandstone  occurs  in  two  or  more  beds  which  are 
separated  by  10  to  15  feet  of  shale.  In  a  few  places  as  many  as  four  sep- 
arate beds  of  sandstone  are  found.  Usually  the  top  sand  is  barren  of  oil, 
but  in  one  or  two  wells  it  has  been  reported  to  make  a  showing.  The  second 
sand  is  generally  the  principal  producing  member  of  the  Carper  sand  zone. 

The  oil  accumulation  in  the  Carper  sand  is  determined  by  a  combination 
of  folding  and  sand  conditions.  The  Carper  sand  is  consistently  productive 
where  found  on  the  higher  parts  of  the  dome,  but  in  some  places  it  is  so 
dense  that  the  wells  are  small.  Good  wells  have  been  obtained  at  some  little 
distance  down  the  dip  from  the  highest  portions  of  the  structure  below 
tighter  places  in  the  Carper  sand,  but  the  presence  of  a  larger  amount  of 
gas  in  the  highest  parts  of  the  fold  has  generally  resulted  in  securing  the 
best  production  there. 

"niagaran"  lime 

The  "Niagaran"  is  a  porous,  weathered  zone  in  the  upper  part  of  the 
Devonian-Silurian  limestone.  The  best  production  has  been  found  from  10 
to  30  feet  below  the  top  of  the  limestone.  In  general  a  large  amount  of 
water  is  produced  with  the  oil  from  this  horizon.  The  proportion  of  oil  is 
considerably  greater  on  the  higher  parts  of  the  fold  than  it  is  down  the  dip. 
The  producing  area  is  bounded  by  territory  in  which  the  proportion  of  oil 
is  very  small,  and  is  insufficient  to  pay  for  the  cost  of  pumping. 

Relation  oe  Production  to  Geologic  Structure 

It  appears  that  predictions  as  to  production  can  he  made  from  a  knowl- 
edge of  structural  conditions  more  confidently  for  the  "Niagaran"  than  for 
the  Carper  sand.  It  is  easily  understood  that  an  entire  lack  of  the  Carper 
sand  could  cause  a  dry  hole  on  a  favorable  part  of  the  structure.  In  addi- 
tion, structural  features  which  are  not  pronounced  enough  to  cause  oil 
accumulation  in  the  "Niagaran"  have  resulted  in  production  from  the  Carp- 
er sand  when  combined  with  favorable  sand  conditions.  A  recent  example 
of  this  type  is  W.  C.  McBride  Rush  No.  24  in  sec.  26,  T.  10  N.,  R.  14  W. 
It  i=  thus  apparent  that  pronounced  folding  should  be  deemed  necessary  for 

luction  from  the  "Niagaran"  but  that  prospecting  for  Carper  sand  pro- 
on  should  be  guided  both  by  a  consideration  of  structure  and  by  the 

1 1  IlifffiiiiM  iiimiii GE0L0GICAL  survey 
3  3051  00005  1528 


PROSPECTING    NEAR  THE    MARTINSVILLE   POOL 
R.  14  WV 


S        ^#fM#/## 


13  W. 


/      tf> 


R.  14  W. 


FIG.   1. 


Fig.  1.  Structure  map  of  the  Martinsville  area  with  contours  drawn  on  the  base 
of  the  Sweetland  Creek  shale.  The  shaded  portions  represent  producing  areas. 
(Drawn  by  G.  F.  Moulton,  Illinois  State  Geological  Survey.) 


4  ILLINOIS    PETROLEUM 

best  available  information  on  sand  conditions.  The  recommendations  in 
this  report  are  primarily  intended  for  prospecting  for  production  from  the 
"Niagaran",  and  are  based  on  the  interpretation  of  the  structural  conditions 
shown  in  figure  1. 

Structure 

The  structure  of  the  area  as  determined  from  deep  well  data  is  shown 
in  figure  1  by  contour  lines  drawn  on  the  base  of  the  Sweetland  Creek  shale. 
The  present  producing  area  lies  on  a  high  part  of  a  dome  which  is  distinctly 
elongated  in  a  northeast-southwest  direction,  and  which  seems  to  represent 
a  local  high  structure  superimposed  on  an  anticline  of  considerable  extent 
having  the  same  trend.  This  axis  of  folding  was  pointed  out  in  an  earlier 
report1  and  an  interpretation  of  more  complete  recent  data  now  shows  that, 
in  the  producing  area  at  least,  it  lies  almost  precisely  as  therein  located. 

It  appears  that  the  principal  fold  continues  beyond  the  limits  of  present 
production,  both  to  the  northeast  and  to  the  southwest.  Although  the  data 
away  from  the  producing  area  are  not  abundant,  what  information  is  avail- 
able justifies  the  interpretation  given  on  the  map.  Wells  which  reach  the 
"Niagaran"  give  no  direct  evidence  of  local  highs  along  the  axis  of  this 
fold,  but  the  alignment  of  shallow  sand  pools  to  the  west  suggests  that  a  high 
might  be  found  along  the  axis  where  the  principal  producing  area  for  the 
shallow  sand  in  Johnson  Township  crosses  it  (approximately  in  sec.  34, 
T.  9  N.,  R.  14  W.).  It  is  further  possible  that  local  doming  may  occur  on 
the  axis  of  folding  to  the  northeast  of  the  producing  area.  This  possibility 
is  also  worth  testing  out. 

The  question  of  the  presence  of  other  axes  of  folding  parallel  to  the 
one  through  the  Martinsville  pool  is  also  of  considerable  importance  to  the 
prospector.  In  the  1923  report,2  a  second  axis  is  shown  a  short  distance 
northwest  of  the  Martinsville  pool,  and  a  third  is  indicated  connecting  the 
North  Casey  and  York  pools.  Both  of  these  axes  trend  parallel  to  the  axis 
through  the  Martinsville  pool. 

More  recent  data  seem  to  indicate  that  there  is  only  a  very  slight  fold 
in  the  position  indicated  for  the  first  axis  northwest  of  the  Martinsville  axis, 
but  that  there  is  a  considerable  probability  that  the  axis  connecting  the  North 
Casey  and  York  pools  represents  a  pronounced  fold. 

Areas  for  Further  Prospecting 

Several  areas  for  further  prospecting  can  be  indicated  at  this  time.  It 
seems  probable  that  the  producing  area  will  be  found  to  extend  from  the 


1  Mylius,  L.  A.,  Oil  and  gas  development  and  possibilities  in  parts  of  eastern  Illi- 
nois:  Illinois  State  Geol.  Survey  Bull.   44C,   1923. 

2  Mylius,   L.  A.,  op.  cit. 


PROSPECTING    NEAR   TIIK    MARTINSVILLE  POOL 


central  part  of  the  field  along  the  axis  of  the  fold  beyond  the  tested  portion. 
Drilling  in  parts  of  sec.  30,  T.  10  N.,  R.  13  W.,  and  sec.  3G,  T.  10  N.,  R.  14 
W.,  near  the  anticlinal  axis  as  shown  on  the  map  and  a  short  distance  from 
the  present  productive  area,  is  worth  while.  These  two  areas  are  suitable  for 
testing"  by  the  operator  who  plans  on  only  one  test  well. 

Drilling  along  the  axis  about  two  miles  southwest  of  the  Martinsville 
pool,  as  well  as  a  short  distance  northeast  of  the  deep  well  in  sec.  26,  T.  9 
N.,  R.  14  W.,  might  result  in  the  discovery  of  other  domes  along  the  Mar- 
tinsville axis.  Each  well  drilled  to  prospect  this  area  should  be  used  to  obtain 
full  information  in  regard  to  sub-surface  conditions.  The  geological  infor- 
mation thus  secured  should  in  turn  be  used  to  modify  the  plan  of  prospecting 
in  accordance  with  the  most  complete  data  available  at  the  time  that  each 
location  is  made.  It  is  only  by  following  such  a  plan  that  thorough  testing 
can  be  accomplished  economically. 

Similar  drilling  should  be  done  a  mile  or  two  northeast  of  the  Martins- 
ville pool  along  the  Martinsville  axis  in  order  to  determine  conditions  there. 

The  prospecting  recommended  should  be  undertaken  by  a  group  who 
can  lease  a  substantial  block  of  acreage  to  safeguard  their  interests,  and  who 
can  drill  three  or  four  wells  in  each  area  tested  before  abandoning  the  project. 

The  area  between  the  North  Casey  and  York  pools  appears  to  merit 
testing  by  a  similar  comprehensive  program  of  drilling  along  the  anticlinal 
axis  indicated  in  that  area.  Three  or  four  wells  might  be  necessary  to  verify 
the  existence  of  the  anticlinal  fold  and  probably  three  more  would  be  suffi- 
cient to  determine  whether  local  structural  highs  may  be  expected  along  the 
axis  if  one  is  found. 

Present  data  on  this  interesting  area  do  not  permit  the  extension  of  the 
structure  map  to  include  it,  but  it  has  been  determined  that  the  strata  rise 
rapidly  to  the  northwest  from  a  point  about  two  miles  northwest  of  the  Mar- 
tinsville axis.  It  is  also  known  that  there  is  a  pronounced  west  dip  a  mile 
or  two  farther  west ;  so  the  presence  of  a  strong  fold  seems  assured.  For 
that  reason  prospecting  in  this  area  should  yield  profitable  results  to  a  group 
having  sufficient  acreage  to  cover  any  pool  which  might  be  found  if  a  pros- 
pecting program  calling  for  the  drilling  of  seven  or  eight  wells  could  be 
undertaken. 

Summary 

The  investigation  of  the  geology  of  the  Martinsville  area  has  determined 
conditions  which  (1)  suggest  the  possibility  of  extending  the  area  of 
"Xiagaran"  production  both  to  the  northeast  and  southwest,  (2)  indicate 
areas  along  the  Martinsville  axis  in  which  other  domes  may  exist,  and  (3) 
strongly  suggest  the  advisability  of  drilling  to  locate  a  parallel  axis  of  fold- 
ing connecting  the  North  Casey  and  York  pools. 


b  ILLINOIS    PETROLEUM 

OIL  INVESTIGATIONS  IN  THE  CENTRALIA  AREA- 
PRELIMINARY  REPORT 

By  Alfred   H.   Bell 

Introduction 

Several  small  oil  fields  are  located  in  the  Centralia  area,  some  of  them 
notable  for  long  duration  of  production.  The  probable  extension  of  geo- 
logical conditions  favorable  for  oil  accumulation  to  other  localities  in  this 
area,  as  well  as  the  possibility  of  finding  deeper  production  in  the  developed 
fields,  has  rendered  desirable  a  more  detailed  investigation  of  the  sub-sur- 
face geology  of  the  area  than  has  heretofore  been  made.  Under  the  direction 
of  the  Illinois  State  Geological  Survey  this  work  was  begun  by  the  writer 
in  the  summer  of  1926.  The  following  is  a  brief  preliminary  report  which, 
since  the  data  obtained  are  not  yet  complete,  should  not  be  taken  as  final. 

Former  Work  in  the  Area 

The  most  complete  study  of  the  geology  of  the  Centralia  area  yet  made 
is  that  by  E.  W.  Shaw1  in  1911.  At  various  other  times  the  area  has  been 
visited  by  members  of  the  Illinois  State  Geological  Survey  and  their  results 
have  been  published.2 

General  Geology 

The  region  is  almost  wholly  covered  with  glacial  deposits.  Outcrops 
of  older  rocks  are  few  and  inadequate  to  give  much  indication  of  the  sub- 
surface structure.  In  making  inferences  with  respect  to  sub-surface  condi- 
tions one  is  therefore  limited  almost  wholly  to  well  and  mine  records. 

Stratigraphy 

A  brief  reference  to  the  succession  of  strata  encountered  in  drilling  is 
in  order ;  for  a  fuller  account  of  the  stratigraphy  the  reader  is  referred  to 
the  Carlyle-Centralia  folio.3  The  strata  which  occur  between  the  base  of 
the  glacial  drift  and  the  top  of  the  Herrin  (No.  6)  coal,  roughly  500  to  550 
feet  in  thickness,  consist  mainly  of  shale  with  a  little  interbedded  limestone 
and  sandstone  and  some  thin  beds  of  coal.     They  are  classified  as  the  Mc- 


1  Shaw,  E.  W.,  U.  S.  Geol.  Survey  Geol.  Atlas,  Carlyle-Centralia  folio  (No.  216), 
1923. 

2  Blatchley,  R.  S.,  Illinois  oil  resources:  Illinois  State  Geol.  Survey  Bull.  16,  pp. 
130-146,   1910. 

St.  Clair,  Stuart,  The  Centralia  area:  Illinois  State  Geol.  Survey  Bull.  35,  pp.  67-73, 
1917. 

Kay,  Fred  H.,  Coal  resources  of  District  VII:  Illinois  Coal  Min.  Inv.  Bull.  11,  pp. 
115-138,   1915. 

3  Shaw,  E.  W.,  op.  cit. 


oil     INVESTIGATIONS    IN    THE   CENTRALIA    AliKA  7 

Leansboro  formation  of  the  Pennsylvanian  system.  For  the  next  300  feet, 
approximately,  shale  belonging  to  the  Carbondale  formation  is  predominant. 
Xext  below  is  about  175  feet  of  sandstone  of  the  Pottsville  formation.  An 
unconformity  separates  it  from  the  underlying  rocks  of  the  Chester  group 
which  belong  in  the  Mississippian  system.  These  rocks  consist  of  limestone, 
sandstone,  and  shale  in  about  equal  amounts.  None  of  the  wells  in  the  area 
described  in  this  report  appear  to  have  been  drilled  below  the  base  of  the 
Chester  rocks  into  the  underlying  Ste.  Genevieve  and  St.  Louis  limestones, 
and  the  Chester  group  in  this  area  is  known  to  have  a  thickness  of  at  least 
500  feet. 

Structure 

Structural  conditions  in  parts  of  the  Centralia  area  are  indicated  on  the 
accompanying  contour  maps  as  follows  :  ( 1 )  An  area  east  and  northeast  of 
Centralia,  with  contours  drawn  on  the  top  of  Herrin  ( Xo.  6)  coal  and  on  the 
top  of  the  producing  sand  (fig.  2).  (2)  An  area  just  south  of  Centralia 
with  contours  drawn  on  the  base  of  Herrin  (No.  6)  coal  (fig.  3).  This  area 
includes  the  Wamac  field. 

Area  East  and  Northeast  of  Centralia 

The  map  in  figure  2  shows  an  anticlinal  nose  whose  axis  trends  north- 
east and  southwest.  It  has  a  relatively  steep  dip  to  the  northwest  and  gentler 
dips  in  other  directions.  An  interesting  relation  is  here  shown  between  the 
productive  area  and  the  structure.  The  producing  wells  are  not  found  on 
the  highest  part  of  the  structure  but  on  the  slopes. 

The  producing  sand  on  which  are  drawn  the  dashed  contours  in  figure 
2  is  in  the  lower  part  of  the  Chester  beds  and  is  about  1,000  feel  below  the 
Herrin  (No.  6)  coal.  It  probably  corresponds  with  the  Stein  sand  of  the 
Sandoval  field.  A  comparison  of  the  contours  shown  on  the  map  brings 
out  the  notable  difference  between  the  structure  on  the  top  of  the  sand  and 
that  on  the  Herrin  (No.  6)  coal.  This  difference  may  be  explained  on  the 
basis  of  (1)  the  unconformity  between  the  Mississippian  and  Pennsylvanian 
systems  and  (2)  irregularities  in  the  deposition  of  the  sand. 

DEVELOPMENT 

Three  small  areas  of  production  are  shown  in  figure  2. 

(1)  The  Ohio  Oil  Company.  Kuester  wells  1  and  2,  NW.  %  SW.  x4 
sec.  3,  T.  1  N.,  R.  1  E.  These  two  wells  have  been  pumped  for  15  years  and 
are  at  present  producing  about  ?  barrels  per  day  of  which  6  barrels  are  from 
No.  1. 

This  company  has  recently  drilled  a  north  offset  to  Kuester  No.  "1  on 
the  Adams  lease  in  the  SW.  %  NW.  M  sec.  3,  T.   1   N..  R.  1  E.     Tt  had  a 


ILLINOIS   PKTROLEUM 


SCALE 


O     D.smond  dull  coal  lis!              •   Pn*mng  «ell 
-<J)-    Or,  hole                                     0    Abandoned  produce 
<D     Drilling  well 

Contours  on  Hemn        Conlours  on  lop  n 

(No  6)tual                                 producing  sand 

6. 

Mcintosh   No.   2 

11. 

Higgins   well 

7. 

Langewisch   No.   1 

12. 

Baker  well 

8. 

Langewisch  No.  2 

13. 

Stater   well 

9. 

Langewisch   No.   3 

14. 

Brown  well 

0. 

Old   Langewisch   No.   1 

15. 

Stater  No.   1 

1.  Adams  No.   1 

2.  Kuester  No.   1 

3.  Kuester   No.    2 

4.  McLellan   No.   1 

5.  Mcintosh   No.   1 

Fig.  2.  Structure  map  of  area  northeast  of  Centralia,  Marion  County.  Shaded 
areas  are  considered  to  have  fair  to  good  possibilities  for  oil  production.  (Drawn 
by  A.  H.  Bell,  Illinois  State  Geological  Survey.) 


OIL   INVESTIGATIONS   IN    THE  CENTBALIA   AREA  » 

showing  of  oil  in  the  producing  sand  of  the  Kuester  which  was  topped  at 
1,601  feet  but  the  well  was  drilled  down  to  1,779;  it  is  being  plugged  back 
to  1,625. 

(2)  The  James  Oil  Company. — Langewisch  wells  1,  2,  and  3,  and  Mc- 
intosh wells  1  and  2,  SE.  34  sec  4,  T.  1  N.,  R.  1  E.  The  production  here 
from  4  wells  is  about  30  barrels  of  which  Langewisch  No.  1  makes  13  bar- 
rels. This  well  was  drilled  in  1919.  It  filled  up  with  oil  and  made  82  bar- 
rels natural  the  first  24  hours.  By  August,  1925,  it  was  making  only  one- 
fourth  barrel.  It  was  then  drilled  10  feet  deeper  to  1,632^  and  shot  with 
40  quarts.  Langewisch  No.  2  was  also  shot  about  the  same  time  with  a 
resulting  increase  in  production.  Langewisch  No.  3  and  Mcintosh  Nos.  1 
and  2  have  been  drilled  during  the  past  year.  The  first  two  of  these  are 
now  being  pumped;  Mcintosh  No.  2,  completed  in  July,  1026,  had  a  show- 
ing of  oil  estimated  at  8  barrels  but  the  well  has  been  abandoned.  These 
data  were  supplied  by  Mr.  George  Timberlake. 

"Old  No.  1  Langewisch"  was  drilled  by  the  Saver  Oil  and  Gas  Com- 
pany in  1910.  At  first  it  made  considerable  quantities  of  gas  and  oil;  it 
was  then  shot  with  80  quarts  and  salt  water  came  in.  so  that  it  had  to  be 
abandoned. 

Another  well  about  300  feet  northwest  of  "Old  No.  1"  had  water  in  the 
sand. 

An  interesting  test  is  being  made  by  Higgins  and  Timberlake  on  the 
Higgins  lease  in  the  SW.  34  sec.  4,  T.  1  N.,  R.  1  E.,  half  a  mile  west  of  the 
Langewisch  wells.  On  August  10  they  were  drilling  at  1.140  and  should 
have  been  at  the  top  of  the  sand  in  two  or  three  days.  If  this  well  is  a  pro- 
ducer from  the  same  sand  as  the  Langewisch  and  Kuester  wells  it  will 
"prove  up"  the  intervening  territory. 

(3)  The  Brown  well  in  the  NE.  34  NW.  )/+  sec.  16.  T.  1  N.,  R.  1  E., 
has  been  pumped  for  15  years  and  is  now  making  5y2  barrels  per  day. 

Attempts  have  been  made  to  extend  production  outwards  from  this 
well  but  so  far  without  success.  The  well  about  a  quarter  of  a  mile  to  the 
southeast,  Stater  No.  1,  is  reported  to  have  made  8  barrels  natural.  It  was 
shot  with  40  quarts  and  then  made  water.  The  dry  hole  in  the  NE.  corner 
NW.  34  °f  the  same  section  was  shallow,  with  a  total  depth  of  810  feet,  so 
that  the  deep  sand  was  not  tested.  The  north  offset  to  the  Brown  well,  on 
the  Stater  land,  had  a  showing  of  oil. 

The  Baker  well  to  the  west,  SW.  corner  sec.  9,  had  water  in  the  sand. 

RECOMMENDATIONS 

On  the  basis  of  the  structure  shown  by  the  contours  drawn  on  the 
Herrin  (No.  6)  coal  and  on  the  producing  sand  there  appears  to  be  a  good 


10  ILLINOIS   PETROLEUM 

opportunity  for  extending  the  producing  areas  northeast  from  the  Kuester 
and  Adams  wells  in  sec.  3  and  southwest  from  the  Langewisch  wells  in 
sec.  4. 

There  appear  still  to  be  good  possibilities  of  extending  the  Brown  pro- 
duction in  sec.  16.  The  territory  between  the  Brown  well  and  the  Stater  well 
to  the  south  is  practically  "proven"  for  small  production.  Although  the 
structural  data  are  meager,  the  contours  in  figure  2  suggest  a  possible  exten- 
sion of  production  to  the  northeast  through  the  SE.  34  sec.  9  and  into  ihe 
SW.  J4  sec.  10.  It  is  also  possible  that  the  oil  pool  may  extend  southwest 
of  the  Brown  well. 

The  shaded  areas  in  figure  2  are  considered  to  have  fair  to  good  pros- 
pects for  oil  production. 

Not  enough  is  known  concerning  the  structure  in  the  remaining  parts 
of  the  area  mapped  to  form  the  basis  for  definite  recommendations  con- 
cerning the  locations  of  wildcat  tests.  No  other  very  favorable  localities  can 
be  pointed  to  in  this  area.  It  may  be,  however,  that,  as  future  drilling- 
progresses,  structural  conditions  will  be  found  to  differ  from  those  shown 
in  figure  2.  and  small  domes  or  terraces  may  exist  whose  presence  is  at  this 
time  unsuspected  and  which  may  have  influenced  the  accumulation  of  oil  in 
commercial  quantities. 

The  fact  that  little  or  nothing  can  be  learned  about  sub-surface  struc- 
ture from  surface  studies  in  this  area  makes  it  all  the  more  imperative  to 
keep  careful  logs  of  all  wells  that  are  drilled  in  the  future.  If  we  had  such 
logs  for  all  the  wells  that  have  been  drilled  in  the  past  our  knowledge  of  the 
sub-surface  geology  would  be  much  fuller  than  it  is,  and  more  accurate  pre- 
dictions could  be  made  concerning  the  locations  of  oil  pools  in  advance  of 
drilling.  The  preservation  of  numerous  samples  of  well  cuttings,  especially 
in  the  vicinity  of  oil  sands,  is  also  of  great  importance  for  a  thorough  geo- 
logical study.  These  samples  should  be  carefully  labelled  as  to  depth  and 
location  of  well.  The  Survey  will  gladly  supply  sample  sacks  for  well  cut- 
tings to  anyone  engaged  in  drilling. 

The  Wamac  Field 

The  Wamac  field  south  of  Centralia  was  opened  early  in  1922;  the 
first  oil  was  discovered  late  in  1921.  The  maximum  flush  production  for 
the  field  was  about  1,200  barrels  per  day;  the  present  production  is  approx- 
imately 125  barrels  of  32°  Baume  oil  from  100  wells.  All  the  oil  is  obtained 
from  a  sand  about  230  feet  below  Herrin  (No.  6)  coal  known  locally  as  the 
"Petro"  oil  sand.     It  has  a  thickness  of  about  30  feet. 

Structural  conditions  are  shown  in  figure  3.  The  data  for  the  map 
were  obtained  from  large  scale  maps  of  No.  2  and  No.  5  mines  owned  by 


OIL   INVESTIGATIONS   IN    THE   CENTKALIA    AU1.A 

R    1  E. 


11 


R   1  W. 


R.  1  W. 
0 


SCALE 


R.  1  E. 
1   mile 


\ 


p      Downthrow  side 


Fig.  3.  Structure  contours  drawn  on  the  base  of  Herrin  (No.  6)  coal  in  area 
just  south  of  Centralia.  Shaded  area  A  shows  extent  of  Wamac  pool.  The  wells 
drilled  in  shaded  area  B  were  formerly  pumped  but  are  now  abandoned.  (Drawn 
by  A.  H.  Bell,  Illinois  State  Geological  Survey.) 


12  ILLINOIS    PETEOLETIM 

the  Centralia  Coal  Company.  Precise  levels  were  determined  by  the  mine 
engineers  through  most  of  the  main  tunnels  and,  as  their  results  are  embodied 
in  the  accompanying  contour  map,  a  higher  degree  of  accuracy  has  been 
attained  in  this  map  than  is  possible  for  most  structure  maps. 

The  important  features  are  the  steep  east  and  southeast  dip,  140  feet 
in  a  little  oyer  half  a  mile,  and  the  relatively  gentle  dip  in  other  directions, 
especially  to  the  west.  The  mine  map  shows  one  fault  trending  a  little  west 
of  north  and  east  of  south,  situated  about  1200  feet  north  and  250  feet  east 
of  the  center  of  sec.  30,  T.  1  N.,  R.  1  E.  The  fault  plane  dips  75°  to  the 
east.  The  displacement  is  3  feet,  and  the  downthrow  side  is  on  the  east.  The 
fault  is  just  outside  and  to  the  east  of  the  productive  area  of  the  Wamac  oil 
field. 

The  present  productive  area  of  the  Wamac  field  is  indicated  by  shaded 
area  A  in  figure  3.  In  all  but  the  extreme  northern  part  production  is  lim- 
ited to  the  highest  part  of  the  structure.  The  boundary  is  known  fairly 
definitely  from  the  positions  of  dry  holes.  One  deep  test  has  been  drilled, 
namely  Petro  Oil  and  Gas  Company's  Frazier  No.  1  (250  feet  south  of 
north  line  and  T30  feet  east  of  west  line  of  SW.  J4  sec.  30)  to  a  depth  of  1,484 
feet.  A  dry  sand  was  encountered  from  1,454  to  1,460  and  a  salt  water 
sand  from  1,4(30  to  1,480  which  was  believed  to  be  the  Benoist  sand.  Since 
this  test  was  drilled  fairly  high  on  the  structure  it  appears  to  condemn  the 
structure  for  possibilities  of  production  in  deeper  sands,  at  least  as  far  as 
the  Benoist. 

The  results  of  a  more  detailed  study  of  the  Wamac  field  will  be  pre- 
sented later. 

oil      (55471—1500—8-26) 


